1. Field
The present disclosure relates to a coolant passage structure for an internal combustion engine.
2. Description of the Related Art
An enormous amount of coolant is supplied to a vehicle-mounted internal combustion engine. If a large pressure drop exists in a coolant system through which that enormous amount of coolant flows, a sufficient cooling ability is not obtainable, and a large water pump and coolant passage are needed. Various examples of water pumps and coolant passage structures are proposed (see, for example, Japanese Patent No. 3342398 and Japanese Unexamined Patent Application Publication No. 2013-108385).
The structure described in Japanese Patent No. 3342398 aims to improve the rigidity of a bracket for mounting auxiliary machinery parts and to cool the auxiliary machinery parts using a coolant passage. That patent literature discloses a water pump, a first coolant passage upwardly extending from a pump chamber in the water pump along a mounting base, and a second coolant passage bent toward a cylinder block from the upper end of the first coolant passage.
The structure described in Japanese Unexamined Patent Application Publication No. 2013-108385 aims to reduce the entire size of an internal combustion engine by arranging auxiliaries, including a water pump, in a compact manner. That patent literature discloses the water pump and a recessed passage forming a downstream-side coolant passage extending from a pump chamber in the water pump toward a cylinder head, being curved at a curved middle portion, extending upwardly, and reaching a coolant supply part at an upper site.